Synthesis, characterization, radiolabeling and biodistribution of a novel cyclohexane dioxime derivative as a potential candidate for tumor imaging.

PURPOSE: Dioxime derivative is reported to exhibit high affinity towards tumor cells. The objective of the present study is to synthesize a new dioxime derivative to be labeled with technetium-99m for using as a solid tumor marker. MATERIALS AND METHODS: ((2E,2',3E,3')-3,3'-(cyclohexane-1,2-diylbis (azanylylidene)) bis-(butan-2-one)dioxime) was synthesized by condensation of Butan-2,3-dione monooxime and diaminocyclohexane and labeled with 99mTc. The in-vivo distribution of the agent was studied by carrying out biodistribution in tumor bearing Albino mice. RESULTS: A new cyclohexane dioxime derivative was synthesized with a good yield of 93 ± 2% and its complexation with 99mTc was prepared with 85 ± 4% radiochemical yield under the optimized conditions and the preparation exhibited in-vitro stability up to 6 h. Biodistribution studies showed high uptake in tumor cells with T/NT (target to non-target ratio) = 3.4 ± 0.2 after 0.5 h post injection. CONCLUSION: As a result of biodistribution studies, the newly synthesized cyclohexane dioxime derivative showed its good uptake in tumor cells, which affords a potential radiopharmaceutical that could be used as a good tumor imaging agent.

Synthesis, preclinical, and pharmacokinetic evaluation of a new zoledronate derivative as a promising antiosteoporotic candidate using radiolabeling technique.

A novel zoledronic acid (ZL) derivative, 3-(2-ethyl-4-methyi-1H-imidazole-1-yl)-1-hydroxy-1-phosphonopropyl phosphonic acid (EMIHPBP), was synthesized, characterized, and successfully radiolabeled with 99m Tc. The in vivo biodistribution of 99m Tc-EMIHPBP was investigated and compared with the previously reported zoledronate derivatives aiming to formulate a novel zoledronate derivative with a high-potential uptake to bone as a promising antiosteoporotic candidate. To further evaluate the bone uptake efficiency, the pharmacokinetics of 99m Tc-EMIHPBP was investigated and showed that maximum concentration in bone (Cmax ) was 31.60 ± 0.15%ID/gram after 60 minutes (tmax ). Cumulative residence of 99m Tc-EMIHPBP in the bone [AUC (0-∞) (%ID∙min/gram bone)] was 3685.23, mean residence time was 384.354 minutes, and the calculated bone bioavailability was 15.831%. Finally, the time needed for half of the 99m Tc-EMIHPBP formulation to be eliminated from bone (t1/2 ) was 263.914 minutes. Excellent bone uptake can be obtained 1-hour postinjection with high bone/blood ratio of 23.76 detected with gamma counter. The biodistribution and kinetic studies could recommend EMIHPBP as a promising antiosteoporotic candidate with high selectivity to the skeletal system and rapid clearance from soft tissues.

An easy and effective method for synthesis and radiolabelling of risedronate as a model for bone imaging.

This study aimed to provide an easy method for synthesis of 1-hydroxy-2-(3-pyridyl) ethylidene bisphosphonic acid monosodium (sod. risedronate) with a high yield of 71%. The synthesized risedronate was labeled with technetium-99 m using two different reducing agents (SnCl2 .2H2 O and NaBH4 ) where NaBH4 gave stable complex and higher radiochemical yield more than SnCl2 .2H2 O. The results showed that, the radiochemical purity of (99m) Tc(NaBH4 )-risedronate was 99.2 ± 0.6% and its stability was up to 6 h. Biodistribution study showed high uptake and long retention of (99m) Tc(NaBH4 )-risedronate in bone starting from 15 min (29 ± 2.5% ID/organ) up to 4 h (35.1 ± 3.2 ID/organ) post injection. This research could introduce an easy and effective method for synthesis and labeling of risedrionate and affording a good tracer for bone imaging.

Labeling of tannic Acid with technetium-99m for diagnosis of stomach ulcer.

Tannic acid is a polyphenolic compound that could be labeled with technetium-99m. To produce about 90% yield of (99m)Tc-tannic acid in acidic media (pH), the conditions required were 150 µg tin chloride, 30 min reaction time, and 200 µg of the substrate. (99m)Tc-tannic was stable for 6 h. Oral biodistribution of (99m)Tc-tannic showed that it concentrated in the stomach ulcer to reach about 50% of the total injected dose at 1 h after orall administration. This concentration of (99m)Tc-tannic in stomach ulcer may be sufficient to radio-image the presence of ulcer in the stomach.

Chemical and thermodynamic characteristics of the isotopic exchange reaction between radioiodine and iodohippuric acid isomers.

The parameters affecting the absolute radiochemical yield of the isotopic exchange reaction between radioiodine (125I-) and iodohippuric acid isomers on molten ammonium acetate as a medium exchange at 120 degrees C without any carrier added (radioiodine, 125I-) was determined. The isotopic exchange reactions of radioiodine as 125I- for iodine-127 of o- and p-iodohippuric acid isomers occur more rapidly than m-iodohippuric acid isomer. These reactions proceed by nucleophilic second order substitution reaction. The kinetics and thermodynamic parameters of these isotopic exchange reactions were determined. The absolute radiochemical yield and radio pharmaceutical purity were determined by HPLC and TLC techniques.